1. Field of the Invention
The present invention relates to a process of manufacture and a manufacturing device of a stator.
2. Background Art
As the structure of a stator coil in a rotating electrical machine, distributed winding, concentrated winding, and the like are known. In particular, a winding structure is known which comprises a first three-phase connection coil obtained by three-phase-connecting three stator coils short-pitch lap-wound around teeth of a stator core at a pitch shorter than the magnetic pole pitch of a rotator, and a second three-phase connection coil obtained by three-phase-connecting three stator coils together which are short-pitch lap-wound around teeth of a stator core at a short pitch so that each of the stator coils is displaced from the corresponding one of the stator coils of the first three-phase connection coil by an electric angle of π/3 radians, the three stator coils being connected together in the same manner as that for the first three-phase connection coil (see JP Patent Publication (Kokai) No. 6-165422 (1994).
In view of the recent energy issue, there has been a demand for the high-efficiency of rotating electrical machines. However, the above-described technique is in principle based on concentrated winding. Thus, the stator coil for one phase utilizes only a region of an interlinkage magnetic flux from the rotator which corresponds to an electric angle of 120 degrees. Hence, it has been increasingly difficult to increase the efficiency of the concentrated winding, compared to that of the distributed winding, which utilizes a region of the interlinkage magnetic flux corresponding to an electric angle of 360 degrees.
On the other hand, the distributed winding includes full pitch winding and short pitch winding. Both in the full pitch winding and in the short pitch winding, the coils for all the phases are wound around the teeth of the stator by winding the coils in one direction through an electric angle of substantially 180 degrees and then in the opposite direction through the remaining 180 degrees. This increases the interlinkage magnetic flux amount by which each coil is interlinked with a magnetic flux whose reaction is caused by a current flowing through the coil. Hence, the inductance of the coil has a relatively large value. Thus, in a dynamo, a generation current is suppressed in a high-speed rotation region. In a motor, the control responsiveness of the coil current is degraded.
The present invention provides a process of manufacture and a manufacturing device which are preferable for a small, high-power rotating electrical machine in which the coils are wound such that two stator magnetic poles each formed of in-phase coil turns are arranged within an electric angle of 360 degrees formed by magnetic poles of the rotor.